## Just Accepted

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Published:   , doi: 10.1088/1674-1137/ac3def
Abstract:
The masses of pion and sigma meson modes, along with their dissociation in the quark medium, provide detailed spectral structures of the chiral partners. One has seen collectivity in pA and pp systems both at LHC and RHIC. In this article, we study the restoration of chiral symmetry by investigating the finite size effect on the detailed structure of the chiral partners in the framework of the Nambu-Jona-Lasinio model. Their diffusions and conductions have been studied through this dissociation mechanism. It is found that the masses, widths, diffusion coefficients, conductivities of chiral partners merge at different temperatures in the restoration phase of chiral symmetry. However, merging points are shifted to lower temperatures when one introduces the finite size effect into the picture. The strengths of diffusions and conductions are also reduced once the finite size is introduced in the calculations.
Published:   , doi: 10.1088/1674-1137/ac3d8c
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In this work, we generate gauge configurations with \begin{document}$N_f = 2$\end{document} dynamical charm quarks on anisotropic lattices. The mass shift of \begin{document}$1S$\end{document} and \begin{document}$1P$\end{document} charmonia owing to the charm quark annihilation effect can be investigated directly in a manner of unitary theory. The distillation method is adopted to treat the charm quark annihilation diagrams at a very precise level. For \begin{document}$1S$\end{document} charmonia, the charm quark annihilation effect almost does not change the \begin{document}$J/\psi$\end{document} mass, but lifts the \begin{document}$\eta_c$\end{document} mass by approximately 3-4 MeV. For \begin{document}$1P$\end{document} charmonia, this effect results in positive mass shifts of approximately 1 MeV for \begin{document}$\chi_{c1}$\end{document} and \begin{document}$h_c$\end{document}, but decreases the \begin{document}$\chi_{c2}$\end{document} mass by approximately 3 MeV. We have not obtain a reliable result for the mass shift of \begin{document}$\chi_{c0}$\end{document}. In addition, it is observed that the spin averaged mass of the spin-triplet \begin{document}$1P$\end{document} charmonia is in a good agreement with the \begin{document}$h_c$\end{document}, as expected by the non-relativistic quark model and measured by experiments.
Published:   , doi: 10.1088/1674-1137/ac3d2b
Abstract:
We propose a two-component dark matter explanation to the EDGES 21 cm anomalous signal. The heavier dark matter component is long-lived whose decay is primarily responsible for the relic abundance of the lighter dark matter which is millicharged. To evade the constraints from CMB, underground dark matter direct detection, and XQC experiments, the lifetime of the heavier dark matter has to be larger than \begin{document}$0.1\, \tau_U$\end{document}, where \begin{document}$\tau_U$\end{document} is the age of the universe. Our model provides a viable realization of the millicharged dark matter model to explain the EDGES 21 cm, since the minimal model in which the relic density is generated via thermal freeze-out is ruled out by various constraints.
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This work explores the scalar and Dirac quasinormal modes pertaining to a class of black hole solutions in the scalar-tensor-Gauss-Bonnet theory. The black hole metrics in question are novel analytic solutions recently derived in the extended version of the latter theory, which effectively follows at the level of the action of string theory. Owing to the existence of a nonlinear electromagnetic field, the black hole solution possesses a nonvanishing magnetic charge. In particular, the metric is capable of describing black holes with distinct characteristics by assuming different values of the ADM mass and the magnetic charge. The present study is devoted to investigating the scalar and Dirac perturbations in the above black hole spacetimes, and in particular, based on distinct horizon structures, we focus on two different types of solutions. The properties of the complex frequencies of the obtained dissipative oscillations are investigated, and subsequently, the stability of the metric is addressed. We elaborate on the possible implications of the present study.
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With the two-fluid TOV equation, the properties of dark matter (DM) admixed NSs (DANSs) have been studied. Different from previous studies, we find that increase of the maximum mass and decrease of the radius of 1.4 \begin{document}$M_\odot$\end{document} can occur simultaneously in DANS. This stems from the fact that the equation of state (EOS) of DM can be very soft at low density but very stiff at high density. It is well known that the IU-FSU and XS models can not reproduce the neutron star (NS) with a maximum mass greater than 2.0 \begin{document}$M_\odot$\end{document}. However, with considering IU-FSU and XS models in DANS, there are always interactions of various DM mass that can reproduce a maximum mass greater than 2.0 \begin{document}$M_\odot$\end{document} and the radius of 1.4 \begin{document}$M_\odot$\end{document} below 13.7 km. The difference of DANS between the DM with chiral symmetry (DMC) and the DM with meson exchange (DMM) becomes obvious when the central energy density of the DM is greater than one of the NM. When the central energy density ratio of the DM is greater than one of the NM, the DMC model with the DM mass of 1000 MeV still can reproduce a maximum mass greater than 2.0 \begin{document}$M_\odot$\end{document} and the radius of 1.4 \begin{document}$M_\odot$\end{document} below 13.7 km. In the same case, although the maximum mass of DANS with the DMM model is greater than 2.0 \begin{document}$M_\odot$\end{document}, the radius of 1.4 \begin{document}$M_\odot$\end{document} with the DMM model will surpass 13.7 km obviously. In two-fluid system, it is worth noting that the maximum mass of DANS can be larger than 3.0 \begin{document}$M_\odot$\end{document}. As a consequence, the dimensionless tidal deformability \begin{document}$\Lambda_{CP}$\end{document} of DANS with 1.4 \begin{document}$M_\odot$\end{document}, which increase with increasing the maximum mass of DANS, could be larger than 800 when the radius of DANS with 1.4 \begin{document}$M_\odot$\end{document} is about 13.0 km.
Published:   , doi: 10.1088/1674-1137/ac3bc7
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The \begin{document}$\eta N$\end{document} interactions are investigated in the hot magnetized asymmetric nuclear matter using chiral SU(3) model and chiral perturbation theory (ChPT). In the chiral model, the in-medium properties of η-meson are calculated by the medium modified scalar densities under the influence of an external magnetic field. Further, in the combined approach of chiral model and ChPT, off-shell contributions of \begin{document}$\eta N$\end{document} interactions are evaluated from the ChPT effective \begin{document}$\eta N$\end{document} Lagrangian, and the in-medium effect of scalar densities are incorporated from the chiral SU(3) model. We observe a significant effect of magnetic field on the in-medium mass and optical potential of η meson. We observe a deeper mass-shift in the combined approach of ChPT and chiral model compared to the effect of solo chiral SU(3) model. In both approaches, no additional mass-shift is observed due to the uncharged nature of η mesons in the presence of magnetic field.
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A systematic study on forward-backward (FB) multiplicity correlations from large systems to small ones through a multi-phase transport model (AMPT) has been performed and the phenomenon that correlation strength increases with the centrality can be explained by taking the distribution of events as the superposition of a series of Gaussian distributions. It is also found that correlations in the \begin{document}$\eta -\phi$\end{document} plane can imply the shape of event. Furthermore, long range correlations originate from the fluctuations associated with the source information. FB correlations allow us to decouple long range correlations from short range correlations, and may provide a chance to investigate the α-clustering structure in initial colliding light nuclei as well. It seems the tetrahedron 16O + 16O collision gives a more uniform and symmetrical fireball, after that emits the final particles more isotropically or independently in the longitudinal direction, indicating that the forward-backward multiplicity correlation could be used to identify the pattern of α-clustered 16O in future experiments.
Published:   , doi: 10.1088/1674-1137/ac39fd
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We investigate quantum kinetic theory for a massive fermion system under a rotational field. From the Dirac equation in rotating frame we derive the complete set of kinetic equations for the spin components of the 8- and 7-dimensional Wigner functions. While the particles are no longer on a mass shell in general case due to the rotation-spin coupling, there are always only two independent components, which can be taken as the number and spin densities. With the help from the off-shell constraint we obtain the closed transport equations for the two independent components in classical limit and at quantum level. The classical rotation-orbital coupling controls the dynamical evolution of the number density, but the quantum rotation-spin coupling explicitly changes the spin density.
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We report a benchmark calculation for the Lipkin model in nuclear physics with the variational quantum eigensolver in quantum computing. Special attention is paid to the unitary coupled cluster (UCC) ansatz and structure learning (SL) ansatz for the trial wave function. Meanwhile, both calculations with the UCC and SL ansatz can reproduce the ground-state energy well, it is found that the calculation with the SL ansatz performs better than that with the UCC ansatz, and the SL ansatz has even fewer quantum gates than the UCC ansatz.
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We study the effects of higher-order deformations \begin{document}$\beta_\lambda$\end{document} (\begin{document}$\lambda=4,6,8,$\end{document} and 10) on the ground state properties of superheavy nuclei (SHN) near the doubly magic deformed nucleus \begin{document}$^{270}{\rm{Hs}}$\end{document} by using the multidimensionally-constrained (MDC) relativistic mean-field (RMF) model with five effective interactions PC-PK1, PK1, NL3*, DD-ME2, and PKDD. The doubly magic properties of \begin{document}$^{270}{\rm{Hs}}$\end{document} are featured by the large energy gaps at \begin{document}$N=162$\end{document} and \begin{document}$Z=108$\end{document} in the single-particle spectra. By investigating the binding energies and single-particle levels of \begin{document}$^{270}{\rm{Hs}}$\end{document} in multidimensional deformation space, we find that the deformation \begin{document}$\beta_6$\end{document} has the greatest impact on the binding energy among these higher-order deformations and influences the shell gaps considerably. Similar conclusions hold for other SHN near \begin{document}$^{270}{\rm{Hs}}$\end{document}. Our calculations demonstrate that the deformation \begin{document}$\beta_6$\end{document} must be considered when studying SHN by using MDC-RMF.
Published:   , doi: 10.1088/1674-1137/ac3749
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The Pauli blocking potential between two colliding nuclei at density overlapping region is applied to describe the heavy nuclei fusion processes. Inspired by the Pauli blocking effect in the \begin{document}$\alpha$\end{document}-decay of heavy nucleus, the Pauli blocking potential of single nucleon from surrounding matter is obtained. In the fusion reactions with strong density overlap, the Pauli blocking potential between projectile and target could be constructed by using a single folding procedure. By consider this Pauli blocking potential, the double folding model with a new parameter set is employed to analyze the fusion processes of total 95 systems. A wider Coulomb barrier and shallower potential pocket are formed in the inner part of potential between two colliding nuclei as compared to the one calculated by the Akyüz-Winther potential. The fusion hindrance phenomena at deep sub-barrier energies are described well for fusion systems \begin{document}$^{16}$\end{document}O + \begin{document}$^{208}$\end{document}Pb and \begin{document}$^{58}$\end{document}Ni + \begin{document}$^{58}$\end{document}Ni.
Published:   , doi: 10.1088/1674-1137/ac3748
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High-order cumulants and factorial cumulants of conserved charges are suggested to study the critical dynamics in heavy-ion collision experiments. In this paper, using the parametric representation of the three-dimensional Ising model which is believed to belong to the same universality class with the Quantum chromo-dynamics, temperature dependence of the second- to fourth-order (factorial) cumulants of the order parameter is studied. It is found that the values of the normalized cumulants are independent of the external magnetic field at the critical temperature, which results in a fixed point in the temperature dependence of the normalized cumulants. In finite-size systems simulated by Monte Carlo method, the fixed point behavior still exists at the temperature near the critical one. The fixed point behavior is also appeared in the temperature dependence of normalized factorial cumulants at least from the fourth-order one. With a mapping from the Ising model to QCD, the fixed point behavior is also found in the energy dependence of the normalized cumulants (or fourth-order factorial cumulants) along different freeze-out curves.
Published:   , doi: 10.1088/1674-1137/ac3642
Abstract:
In our previous work [Phys. Rev. C 101, 014003 (2020)], the photoproduction reaction \begin{document}$\gamma p \to K^{\ast +} \Lambda$\end{document} has been investigated within an effective Lagrangian approach. There, the reaction amplitudes were constructed by including the t-channel K, \begin{document}$K^\ast$\end{document}, and κ exchanges, the u-channel Λ, Σ, and \begin{document}$\Sigma^\ast$\end{document} exchanges, the s-channel N, \begin{document}$N(2000)5/2^+$\end{document}, and \begin{document}$N(2060)5/2^-$\end{document} exchanges, and the interaction current. It has been shown that the data on both the differential cross sections and the spin density matrix elements were simultaneously and satisfactorily described. In this paper, we study the photoproduction reaction \begin{document}$\gamma n \to K^{\ast 0} \Lambda$\end{document} based on the same reaction mechanism as that of \begin{document}$\gamma p \to K^{\ast +} \Lambda$\end{document} with the purpose of getting a unified description of the data for both \begin{document}$\gamma p \to K^{\ast +} \Lambda$\end{document} and \begin{document}$\gamma n \to K^{\ast 0} \Lambda$\end{document} within a same model. All hadronic coupling constants, form factor cutoffs, and the resonance masses and widths in the present calculations remain the same as in our previous work for \begin{document}$\gamma p \to K^{\ast +} \Lambda$\end{document}. The available differential cross-section data for \begin{document}$\gamma n \to K^{\ast 0} \Lambda$\end{document} are well reproduced. Further analysis shows that the cross sections of \begin{document}$\gamma n \to K^{\ast 0} \Lambda$\end{document} are dominated by the contributions of the t-channel K exchange, while the s-channel \begin{document}$N(2000)5/2^+$\end{document} and \begin{document}$N(2060)5/2^-$\end{document} exchanges provide considerable contributions as well.
Published:   , doi: 10.1088/1674-1137/ac3643
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We develop the regular black hole solutions recently proposed in [1] by incorporating the 1-loop quantum correction to the Newton potential as well as a time delay between an observer at the regular center and that at infinity. We define the maximal time delay between the center and the infinity by scanning the mass of black holes such that the sub-Planckian feature of Kretschmann scalar curvature is preserved during the whole process of evaporation. We also compare the distinct behavior of Kretschmann curvature for black holes with an asymptotically Minkowski core and those with an asymptotically de-Sitter core, including Bardeen and Hayward black holes. We expect that this sort of regular black holes may provide more information about the construction of effective metric for Planck stars.
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In this study, the heavy to heavy decay of \begin{document}$B^0_s\rightarrow D^{*+}D^-$\end{document} is evaluated in the factorization approach by using the final state interaction as an effective correction. Under the factorization approach, this decay mode occurs only through the annihilation process, so it gives a small amount. Feynman's rules state that six meson pairs can be imagined for the intermediate states before the final meson pairs are produced. By entering the effects of twelve final state interaction diagrams in the calculations, a significant correction is obtained, so that these effects correct the value of the branching ratio obtained by pure factorization approach from \begin{document}$(2.41\pm1.37)\times10^{-5}$\end{document} to the value of \begin{document}$(8.27\pm2.23)\times10^{-5}$\end{document}. The value obtained for the branching ratio of \begin{document}$B^0_s\rightarrow D^{*+}D^-$\end{document} decay is well consistent with the experimental result.
Published:   , doi: 10.1088/1674-1137/ac3567
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In order to confirm the existence of the dibaryon state \begin{document}$d^*(2380)$\end{document} observed at WASA@COSYìwe estimate the production of the possible dibaryon and anti-dibaryon pair \begin{document}${d^*}{\bar{d}^*}$\end{document} at the energy region of the upcoming experiments at \begin{document}${\bar{{\rm{P}}}}$\end{document}anda. Based on some qualitative properties of \begin{document}${d^*}$\end{document} extracted from the analysez in the non-relativistic quark model, the production cross section for this spin-3 particle pair are calculated with the help of an phenomenological effective relativistic and covariant Lagrangian approach.
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The cross sections of the 58,60,61Ni( n, α) 55,57,58Fe reactions were measured at 8.50, 9.50 and 10.50 MeV neutron energies based on the HI-13 tandem accelerator of China Institute of Atomic Energy (CIAE) and the enriched 58Ni, 60Ni, and 61Ni foil samples with backings. A twin gridded ionization chamber (GIC) was used as the charged particle detector, and an EJ-309 liquid scintillator was used to obtain the neutron energy spectra. The relative and absolute neutron fluxes were determined via three highly enriched 238U 3O 8 samples inside the GIC. The uncertainty of the present data of the 58Ni( n, α) 55Fe reaction is smaller comparing with most existing measurements. The present data of 60Ni( n, α) 57Fe and 61Ni( n, α) 58Fe reactions are the first measurement results above 8.00 MeV region. The present experimental data could be reasonably reproduced by calculations with TALYS-1.9 by adjusting several default values of theoretical model parameters.
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In the present paper, we study the effect of the rotation on the masses of scalar meson as well as vector meson in the framework of 2-flavor NambuɃJona-Lasinio model. The existence of rotation causes a tedious quark propagator and corresponding polarization function. Applying the random phase approximation, the meson mass is calculated numerically. It is found that the behavior of scalar and pseudoscalar meson masses under the angular velocity ω is similar to that at finite chemical potential, both relied on the behavior of constituent quark mass and reflect the property related to the chiral symmetry. However, masses of vector meson ρ have a more profound relation with rotation. After analytical and numerical calculation, it turns out that at low temperature and small chemical potential, the mass for spin component \begin{document}$s_z = 0,\pm 1$\end{document} of vector meson under rotation shows very simple mass splitting relation \begin{document}$m_{\rho}^{s_z}(\omega) = m_\rho(\omega = 0)-\omega s_z$\end{document}, similar to the Zeeman splitting of charged meson under magnetic fields. Especially it is noticed that the mass of spin component \begin{document}$s_z = 1$\end{document} vector meson ρ decreases linearly with ω and reaches zero at \begin{document}$\omega_c = m_\rho(\omega = 0)$\end{document}, this indicates the system will develop \begin{document}$s_z = 1$\end{document} vector meson condensation and the system will be spontaneously spin-polarized under rotation.
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We have calculated the potential energy surfaces (PESs) for 240Pu up to scission point using the density functional theory (DFT) with different pairing strengths to investigate the effect of the pairing correlations on the fission properties. The enhancement of pairing correlations lowers the barrier heights, isomeric state, and the ridge between symmetric and asymmetric fission valleys significantly, weakens the microscopic shell structure around Fermi surface, shrinks the scission frontiers especially for the symmetric and very asymmetric fission regions, and lifts the total kinetic energies (TKEs) for the symmetric fission region. It is also emphasized that the microscopic calculation qualitatively reproduces the trend of the distribution of measured TKEs, especially for the positions of the peaks at \begin{document}$A_{\rm{frag}}\simeq132$\end{document} and \begin{document}$A_{\rm{frag}}\simeq108$\end{document}.
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In this paper, we consider the possibilities of generating baryon number asymmetry in thermal equilibrium within the frameworks of teleparallel and symmetric teleparallel gravities. Through the derivative couplings of the torsion scalar or the non-metricity scalar to baryons, the baryon number asymmetry is indeed produced in the radiation dominated epoch. For gravitational baryogenesis mechanisms in these two frameworks, the produced baryon-to-entropy ratio is too small to be consistent with observations. But the gravitational leptogenesis models within both frameworks have the possibilities to interpret the observed baryon-antibaryon asymmetry.
Published:   , doi: 10.1088/1674-1137/ac31a4
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Extensive dynamical \begin{document}$N/D$\end{document} calculations are made in the study of \begin{document}$S_{11}$\end{document} channel low energy \begin{document}$\pi$\end{document}N scatterings, based on various phenomenological model inputs of left cuts at tree level. The subtleties of the singular behavior of the partial wave amplitude at the origin of the complex \begin{document}$s$\end{document} plane are carefully analysed. Furthermore, it is found that the dispersion representation for the phase shift, \begin{document}$\delta$\end{document}, has to be modified in the case of \begin{document}$\pi$\end{document}N scatterings. An additional contribution from the dispersion integral exists, which is, however, almost exactly cancelled the contribution from two virtual poles located near the end points of the segment cut induced by \begin{document}$u$\end{document} channel nucleon exchanges. Relying very little on the details of the dynamical inputs, the subthreshold resonance \begin{document}$N^*(890)$\end{document} survives.